1. Field of the Invention
The present invention relates generally to motor parts and more specifically, to a carbon brush holder for use in a motor.
2. Description of the Related Art
Referring to FIG. 1 and FIG. 2, a conventional carbon brush holder mainly comprises an insulated housing 1 and a carbon brush-holding member 2 made of copper. The insulated housing 1 has a through hole with a first section 1a for insertion of the carbon brush-holding member 2 and a second section 1b, which is larger in diameter than the first section 1a such that a stepped portion is formed therebetween the first section 1a and the second section 1b. The second section 1b is provided at an inner periphery thereof with an internal thread 1c. When the conventional carbon brush holder is assembled, a carbon brush 3, which is electrically connected with a conductive member 6 through a lead wire 4 and a spring 5 surrounding the lead wire 4, is inserted into carbon brush-holding member 2, and subsequently a cover 7 is threaded into the internal thread 1e of the insulated housing 1 to press and force the conductive member 6 to be in contact with the top end face of the carbon brush-holding member 2. Thus, the carbon brush-holding member 2 can supply power to the carbon brush 3 through an external power source.
As indicated above, the conductive member 6 and the carbon brush-holding member 2 have to be closely contacted with each other for enabling the electric current to flow through the carbon brush-holding member 2, the conductive member 6, the lead wire 4, and finally the carbon brush 3 by contact conduction. However, the top end face of the carbon brush-holding member 2 is flush with the stepped portion of the insulated housing 1 in the optimum condition due to the restriction of the internal thread 1c of the insulated housing 1, resulting in that the conductive member 6 may be blocked by the stepped portion of the insulated housing 1 to cause discontact of the conductive member 6 from the copper carbon brush-holding member 2. Such imperfect or malfunctioned conduction between the conductive member 6 and the carbon brush-holding member 2 will generally cause arcs and sparkles or incomplete conduction of electricity.